1. Field of the Invention
The present invention is generally directed to interactive systems for selectively distributing multimedia presentations to viewers at the time the viewers submit requests for the presentations. The invention is concerned with systems where a user tunes a device, such as a television set or personal computer, to a predetermined channel frequency within any of a number of suitable transmission media, and selects one from a large number of program or service options via an upstream communications path through which navigation is implemented.
2. Description of Related Art
A variety of communication systems are available to provide voice, data, image and video services to system users. The distribution media can be twisted-pair; coaxial or fiber-optic cable; or terrestrial or satellite over-the-air transmission. The communication system can be “two-way,” comprised of like media, or a hybrid. For example, a hybrid system can include broadcast or cable media to the user and telephone from the user. Twisted-pair facilities can be used in a bi-directional mode to distribute data-objects, or images, of high information content (millions of binary digits). However, as the information content grows, the time to transmit the information to the remote terminal also grows to an often impractical delay for such bi-directional twisted-pair facilities.
Broadband techniques via coaxial cable and fiber-optics appear to promise the better, long-term solutions. In particular, interactive cable television systems have been developed to distribute information on demand, including entertainment and information programming, education, catalog shopping and financial transactions. Generally, a subscribing user of such a system sends a signal indicative of desired information to a central location, at which a scripted presentation is assembled. The scripted presentation is uniquely addressed to the requesting user, and directed to equipment located at the user premises. Such interactive cable television systems have been described in U.S. Pat. No. 4,734,764, granted to Pocock et al. on Mar. 29, 1988. In one embodiment of the U.S. Pat. No. 4,734,764 patent, individually addressed video frames are assembled at the server into a non-contiguous variant of the 30 frame-per-second, video transmission standard, as defined for the United States by the National Television Standards Committee (NTSC). The 30 frame per second NTSC approach is also encountered elsewhere in the world, but a variety of alternatives are also employed. Those seen most often are the 25 frame per second repetition rates mandated by the European standards Phase Alternation Line-rate (PAL) and SEquential Color And Memory (SECAM).
The video frames, defined by the governing standard, are individually retrieved from a suitable video storage medium, and each frame contains an embedded address that uniquely identifies addressable processing apparatus in the system to which the requesting viewer is connected, such as the video frame store described below. All presentations, as sequentially and/or simultaneously requested by users, are assembled and multiplexed into an NTSC video stream for transmission to users through an over-the-air channel, or through a channel within cable facilities. Addressable frame storage means can be located anywhere between the central storage/assembly area and the user-premises. The storage means can be located, for example, at transmission nodes within a cable television distribution system, or they may be located within television receiving devices at the premises of the user requesting the service. The system disclosed in the U.S. Pat. No. 4,734,764 patent provides a practical approach that enables the selective distribution of video presentations to be implemented economically within a conventional television system having a finite number of available channels.
The U.S. Pat. No. 4,734,764 describes the interactive distribution of still-frame video and accompanying audio along with overlay graphics through a television distribution system to a television set in the home of a user. The transmission can be accomplished by antennae located at both the distribution point and the user's home, by a satellite with retransmission to a home user's “dish,” by a coaxial-cable network, a fiber-optic cable, via a fiber-optic and coaxial-cable hybrid, or by some other transmission means.
The U.S. Pat. No. 4,734,764 patent also describes a reception/processing/formatting device known as a video frame store, or “frame grabber” (some of this description is provided from column 12, line 64 through column 14, line 43 of the U.S. Pat. No. 4,734,764). The frame-grabber can be shared among a number of users, or assigned to a single user. In either case, the video frame store has means to store and forward either a single video frame, or a motion picture sequence of specified duration, depending upon the storage (or buffering) capacity of the frame store in question. The storage location is uniquely addressed to the requesting user. Identification codes assigned to users can be encoded within the vertical blanking interval of an NTSC video frame, or embedded within an in-band or out-of-band control stream directed to the frame stores.
In a preferred embodiment, the video frame store has means to receive, from either a primary or a secondary path, an audio accompaniment to the video. The frame store can be at either a primary or secondary distribution node, or on the customer premises, as described in more detail in U.S. Pat. No. 5,014,125, granted to Pocock et al. on May 7, 1991. Alternatively, the frame store can be part of either the user's television set or an ancillary television converter system, provided by either the user, an over-the-air distribution company, or a Community Antenna Television or Cable TV (CATV) operator.
Increased functionality and effectiveness of the U.S. Pat. No. 4,734,764 system is provided by U.S. Pat. No. 4,792,849, granted to McCalley et al. on Dec. 20, 1988. The U.S. Pat. No. 4,792,849 describes a “digital” embodiment for accomplishing the objectives of the U.S. Pat. No. 4,734,764 within a distributed-network architecture. The system employs a network interface through which user-requests are received at a local area network (LAN) within a central site. Data processors dedicated to user-session tasks are also operatively connected to the central site LAN. The user session tasks include subscriber identification, navigation, maintaining usage logs, and the large scale storage and retrieval of digitally formatted multi-media presentations of products, services and information. Distribution from the central site is typically performed within the digital facilities of a broadband distributor such as a CATV operator. Digital to analog conversion of the requested multimedia presentations can be accomplished at the user premises, or at suitably equipped nodes within the CATV (or other) system. Nodes can be located at the CATV head-end or at distribution hubs within the CATV distribution network.
U.S. Pat. No. 4,829,372, granted to McCalley et al. on May 9, 1989 discloses a presentation player for receiving a stream of digital packets, including packets assembled similarly to the scheme described in the U.S. Pat. No. 4,792,849. The packets can be transmitted over-the-air or through a cable distribution trunk. The receipt of the digital packets can occur at a device located either at a distribution system node or at the premises of a requesting user. Destination addresses appear within the header of each packet. Upon receipt at each destination to which they were uniquely addressed, the packets are converted into a video presentation with accompanying audio and are forwarded to the requesting user.
It is desirable to build upon the fundamental principles disclosed in the U.S. Pat. Nos. 4,734,764, 4,792,849 and 4,829,372 and their derivatives. There is a need for a distribution method and system that uses the video channel in an economic manner and minimizes user contention as the number of users in the system increases. This need is not addressed by distribution systems and methods disclosed in the background art.